Field of the Invention
The invention relates to a method for controlling air volume provided by a motor and by an air-conditioning fan system.
Description of the Related Art
In an indoor ventilation duct of a household air-conditioner, static pressure often changes because of dust deposition in a duct or blockage of a filter. The static pressure is often higher than the standard static pressure for a nominal system in a manufacturer laboratory. Constant air volume control can provide constant air volume for users under such cases, so as to maintain the comfortable ventilating, cooling or heating effect under broad static pressure conditions.
To realize constant air volume, an air volume meter can be installed. However, this increases the cost and the risk of failure. In addition, rotational speed can be adjusted by monitoring the changes of static pressure. A typical method for determination of the air volume is to directly measure the external static pressure, which requires that the relationship between the static pressure and air volume is measured in advance, then the torque of a motor is calculated under the static pressure corresponding to the specified air volume, and speed adjustment is carried out by monitoring the changes of static pressure. This, however, requires a powerful microprocessor control unit (MCU), which further increases the cost.